Friday, December 15, 2017

Something to Crow About: Happy Hooking, a Relatively New Tool Skill

      New Caledonian crows are the only species besides humans known to manufacture hooked tools in the wild. These birds produce these remarkable tools from the side branches of certain plants, carefully 'crafting' a crochet-like hook that can be used for snagging insect prey.




      The study, published in Current Biology on December 7, 2017, reveals how crows manage to fashion particularly efficient tools, with well-defined 'deep' hooks.




      The hook is widely regarded as one of humankind's most important innovations, with skillful reshaping, a useless piece of raw material is transformed into a powerful tool. While our ancestors started making stone tools over 3 million years ago, hooks are a surprisingly recent advance; the oldest known fish hooks are just 23,000 years old.




         Project leader Dr. Christian Rutz has conducted field research on New Caledonian crows for over a decade. His team recently noticed that crows' hooked tools vary considerably in size and shape. While some tools only exhibit a small extension at the tip, others have deeper hooks.





     Dr. Rutz explains: "We suspected that tools with pronounced hooks are more efficient, and were able to confirm this in controlled experiments with wild-caught crows. The deeper the hook, the faster birds winkled (to extract with difficulty) bait from holes in wooden logs."




     This finding raised the intriguing question of what it takes to make such well-formed hooks. The researchers started planning their study by imagining how humans would approach a comparable task. "When a craftsperson carves a tool from a piece of wood, two things ensure a quality product: good raw materials and skill," Dr. Rutz said.




      Researchers found that the same, apparently, applies to New Caledonian crows. The researchers discovered that the depth of the hook was influenced by both the properties of the plant material, and the technique crows used for detaching branches. When birds made controlled cuts with their sharp bills, the resulting hooks were significantly deeper than when they used a 'sloppier' alternative method of simply pulling off branches. Careful cutting may leave more wooden material at the tip of the stick from which the hook can subsequently be 'sculpted'.






     Surprisingly, adult crows, which are expected to have considerable tool-making experience, did not produce the deepest hooks and regularly employed the 'quick-and-dirty' manufacture technique. Dr. Rutz notes that making very deep hooks may not be the best strategy in the wild: "It probably takes more time and effort to make such tools, and experienced birds may try to avoid these costs. It is also possible that deep hooks break more easily when inserted into narrow holes and crevices."




      Dr. Christophe Boesch, a world-leading chimpanzee expert and Director of the Max Planck Institute of Evolutionary Anthropology in Leipzig, Germany, comments: "We have recently discovered that chimpanzees routinely use naturally-hooked stems to fish for algae, but they don't actively craft these hooks. The crows can reshape plant material with their pointed bills, which act like 'precision pliers', but this would be very difficult for chimpanzees with their large fingers."




     The present study is the first to examine in a non-human animal what factors determine the morphology of crafted tools, and as a consequence, their foraging efficiency. Paleo-anthropologists try to understand how our ancestors produced relatively complex tool shapes from basic raw materials, such as wood, bone or seashell, but they face the challenge that the manufacture process cannot be directly observed.




      The New Caledonian crow, with its remarkable ability to fashion hooked tools from plant stems, provides a fascinating window into humans' evolutionary past.

Hooked on Crows,
Steph

32 comments:

  1. I am marveling at the skill needed to snag an insect and keep your tool from falling off the log while eating said insect. {Click on the "snagging insect prey" link in the first paragraph.}

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  2. Yeah, I was even more impressed with the footwork than with the beakal dexterity. And I'm seeing the word "grub" in a whole new light.

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    1. Yes, quite fancy footwork there to step on the tool and munch away. It amazes me to think of using a tool standing on a limb 20 feet up and then stepping on the tool while snacking on bugs. Smart bird brains!

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  3. Crows are pretty smart. I'm not much of a birder, but I've been impressed by the cooperative predatory behavior I've watched them exhibit. I saw a group of them corner a sparrow outside a big floor-to-ceiling window. One then grabbed the smaller bird and they flew off with it.

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    1. Ah, sparrow me those details, please.

      I prefer to think of crows eating bugs and larvae.

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    2. I've been impressed by cooperative predatory behavior, but never in a positive way.
      #me neither

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    3. Paul, on point.

      It grubs me the wrong way. . .

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  4. Earlier this week as I was walking around Green Lake I almost didn't notice a large Heron standing on some jagged rocks right at the water's edge. I was not more than 2 feet to its left when I saw it. It was not at all concerned about me, and no one else was present. The heron was as still as a Confederate statue in Alabama as it stared into the water, ready to strike at something tasty.

    I stayed and watched for about ten minutes and it then abandoned that site and moved about six feet ahead and again positioned itself. Now, here is where it gets interesting.

    The bird bent its long neck and head into the exact position it desired and then took two or three short steps backward, and while it did this the head was absolutely steady and unmoving as the neck extended while the rest of the body backed up. I watched it do this 2 or 3 times and still cannot figure out how this is possible.

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    1. Nice pics, but not what I saw this time. Also this was a huge Great Blue Heron, much larger than in most of those videos, and none of them show a heron fishing the way I saw this time. I wish I had had my camera with me. Herons have different methods of fishing that seem to depend on what they are after.

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    2. Hope you will go back with your camera!

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    3. Yeah, I am hoping to. I have been walking that lake all my life and sometimes see a Blue Heron, but never doing this. This bird was not looking for fish, but something very tiny, so it had to fish differently. There are fish in the lake, but he was fishing too close to some rocks for fish to get into. Also the head was not more than about ten inches above the water. So what he would do is walk to where he wanted to stand and then, with his very long neck mostly compressed, extend it a little and position it exactly where he wanted, and then he would slowly back up, and this caused his neck to extend much further as his whole body retreated to the exact position he wanted to stand and wait in. The whole time though, his head remained in frozen position. I would love to know how this can be accomplished.

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    4. On rides in the Great Swamp, I bike through a pricey part of Harding Township, past a big house with a koi pond (with a fountain they keep running most of the year). More than once, I've seen a great blue heron standing at the edge, selecting his breakfast.

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    5. Maybe SDB's heron was simply looking for a stalking stuffer....

      Berkeley's Aquatic Park, only feet away from I-80, is a popular spot for professional nature photographers to take pics of herons and egrets. They are so used to human presence that they ignore us, as long as we don't have dogs. I was stuck in traffic in Sonoma County a few years ago and an egret walked so close a passenger could have reached out and petted/ fed/ had her hand bit off.

      Seems odd that the bird would hold its head still and move its body, but what do we know? Maybe it was trying to stir up its prey by moving? Birds have been around a lot longer than humans are likely to be.

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    6. eco:
      No, I knew what the Heron was doing. It had moved into a new fishing spot and first got close and positioned its head exactly where it wanted it to be. Then it moved the rest of its body backwards into the position it wanted to stay in. I realized it did not want to be moving its head while doing all this, which might be perceived by whatever might be nearby and notice a slight change in lighting or something like that. But it was so contrary to all we know about how bodies work. We cannot comprehend how a head can not move while the neck on back does. I can't anyway.

      Anyway I just now returned from a Sierra Club party with wine and dancing and food and all that. I saw a guy using his smart phone to take a photo of people dancing and asked him to show me how to do that with my new smart phone that I have not fully figured out yet. He showed me how to take the photo, which was what I wanted to know, and I then saw that I had indeed taken some pictures of the Heron. At least one is video, but I still do not know how to view it or upload it yet. I doubt it will be of him doing the head dance, but I will try and figure it out and find a way to upload and share.

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    7. eco, I enjoyed stalking stuffer.

      sdb, maybe you can upload the images to Dropbox and send us the link.

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    8. Yesterday I figured out how to view the pics and one video on my smartass phone, but need to do more work to email them; I tried. However, I took these after I had watched several minutes and took the pics from a farther away spot than where I first saw the bird. After that the heron walked ahead several feet and I moved up about 3 feet from where he moved to and he began doing his strange positioning and I did not film it. I wish I had had my regular camera with me.

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    9. sdb, you can save a video to Youtube and add a link to that here.

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    10. Not until I figure out how to move it off my phone and onto my computer.

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    11. I save and share videos on my phone all the time. Go to your video and choose the "share to" symbol (on my Android phone, it's a branch). Choose "Youtube" and your video file is shared to your account. You can then share that link with us.

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    12. I tried the first part of doing that with the intention of emailing it, but I haven't properly set up my email to flirt with my cell phone. Last night I tried something different that did not fully work, and then about once an hour my phone would ring once with no indication why. I finally figured out it had to do with the pictures and my email attempt now being a DRAFT, and I don't know where this is to be found.

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  5. Did you see "Bird Brain" the PBS Nova show last night? Parrots, Keas, and Caledonian Crows shown at their best.

    Happy Solstice, all. May some light return soon.

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  6. I will look for the Bird Brain program on PBS. Thanks for the heads up.

    I echo your happy solstice wishes. More light is coming!

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  7. I wish Word Woman and all the followers of her wonderful PEOTS blog a Merry Christmas and a great 2018.
    I would love to see skydiveboy's video also. Hope he can figure out how to get it onto youtube. He has a better shot of succeeding than I would. I couldn't even figure out how to simply watch Blaine's Christmas video! (Thanks to jan for his help.)
    eco's bon mot in the above comments might be helpful for solving one of my Christmas-themed puzzles in this week's Puzzleria!

    LegoWhoDetectsPeaceAtLeastInOurTriBlogosphere...IfNotOnEarthAlas

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    1. Merry Christmas to you, too, Lego. Thanks so much for your support and greetings! Here's to many videos, photos, and comments in 2018!

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    1. Oddly fascinating. Thanks, jan.

      Maizie is home after a day of dental surgery with some needed extractions. Longer day for her, of course, but it was rather long for me, too. She is home and doing well. She's asleep with her mouth drool on my neck.

      Happy 2018 all!

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  9. New post on "2017: 74 Interesting Science, Technology, and Health Links" is now up. Enjoy!

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